Stucco and water
Traditional stucco is a cement-based plaster applied over lath and a weather-resistant barrier. It absorbs water and releases it as it dries. That is fine in moderation, but repeated soaking, especially at the base of walls, leads to staining, efflorescence (white mineral deposits), cracking and, if water gets behind the stucco, damage to sheathing and framing. Synthetic stucco systems have their own moisture sensitivities.
The wall behind stucco is designed to drain. At the bottom of the wall, a weep screed lets water that gets behind the stucco escape. Building codes, including the IRC section on exterior plaster as adopted in states like Minnesota, require the weep screed to sit at least 4 inches above the earth or 2 inches above paved areas so it can drain.
Splash-back at the base of the wall
Without gutters, roof water falls in a line along the house and splashes back onto the lower wall. Mud and water hit the stucco right at the weep screed. Over time, soil and mulch build up, the weep screed gets buried, and the base of the wall stays wet. That is one of the most common sources of stucco damage. Gutters stop most of this splash. Keeping soil and mulch below the weep screed and using a gravel strip along the foundation helps too.
Staining and streaking
Roof water running down stucco walls, from short overhangs, overflowing gutters or leaking corners, leaves dark streaks and mineral stains that are hard to clean. Properly sized gutters with sealed corners and no overflow keep walls clean. See leaking gutter seams and corners.
Attaching gutters and downspouts on stucco
On many stucco homes, gutters hang from a wood fascia at the eave, just as on other homes. Downspouts, however, run down stucco walls and are strapped to them. Each fastener through stucco is a potential leak and crack point. Good practice:
- Drill (do not hammer) through stucco to avoid cracking.
- Fasten into framing or solid backing, not just the stucco skin.
- Seal each penetration with a sealant compatible with stucco.
- Use corrosion-resistant fasteners and straps.
- Keep the downspout slightly off the wall so it does not trap water against the stucco.
Where possible, reuse existing strap locations when replacing downspouts, and patch old holes with stucco-compatible patching material.
Where downspouts discharge
Downspouts on stucco homes should discharge well away from the wall, never onto the stucco base or soil piled against it. Extensions onto splash blocks, gravel beds or buried lines carry water away. Many stucco homes are on slabs in dry climates, where clay soils swell when soaked. Spreading water away from the foundation protects both the slab and the stucco. See downspouts and your foundation.
Tile roofs and stucco
Stucco walls are often paired with clay or concrete tile roofs, especially in California, Arizona, Florida and Texas. Tile roofs need gutters with compatible hangers, and the eave closures must let water drain into the gutter. See gutters on tile roofs.
Flat roofs and scuppers
Pueblo and Spanish-style stucco homes with flat roofs drain through scuppers or canales. Water thrown from a scupper should land in a conductor head and downspout or on a splash basin well away from the wall, not run down the stucco. See gutters for flat roofs and scuppers.
Signs of water trouble on stucco
Look for dark staining or efflorescence at the base of walls or below roof edges, cracks radiating from downspout straps or window corners, soft or hollow-sounding stucco, peeling paint on stucco, and soil or mulch covering the weep screed. Inside, look for damp baseboards or stains on interior walls behind problem areas. Early repair of the water source, often a gutter or downspout, prevents expensive stucco remediation.
Cracks around downspouts and windows
Hairline cracks in stucco are common and often cosmetic, but cracks that radiate from downspout straps, window corners or roof-wall intersections can let water in. Water running down a wall from a leaking gutter corner or an overflowing section concentrates in those cracks. Fixing the gutter leak first, then having cracks sealed with stucco-compatible materials, keeps water out of the wall.
Roof-wall intersections
Where a lower roof meets a stucco wall, a kick-out flashing should direct water into the gutter instead of down the wall. Missing kick-outs are a leading cause of hidden damage behind stucco. If you see stains or soft stucco below a roof-wall intersection, ask a roofer or stucco specialist to check the flashing. See drip edge and gutter apron.
Partial gutters on stucco homes
In dry climates, some stucco homes do without gutters on every edge. If that is the case, focus gutters where water causes the most trouble: over entries, patios and walkways, along walls where splash reaches the stucco, and anywhere the roof concentrates water from valleys. See gutters in dry climates.
Maintenance for stucco homes
Once a year, walk around the house and look at the base of each wall: is the weep screed visible above soil and mulch? Are downspout extensions in place? Are there new stains below gutter corners or roof edges? After heavy storms, check that gutters did not overflow onto the walls. These quick checks catch problems while they are cheap to fix. Photograph problem spots so you can compare them from year to year.
Colors
Gutters and downspouts on stucco homes are often painted or ordered in a color matching the stucco or trim so they blend in. See how to choose gutter color.